Microparticle production process and apparatus

Abstract

Provided is an apparatus for producing solid polymeric microparticles, the apparatus comprising a plurality of liquid droplet generators for forming liquid droplets of a first liquid, and a nozzle for forming a jet of a second liquid, wherein the plurality of liquid droplet generators and the nozzle are arranged relative to each other such that, in use, liquid droplets from the plurality of liquid droplet generators pass through a gas into said jet of second liquid. Also provided is a process for producing solid microparticles, the process comprising: providing a first liquid comprising a solute and a solvent, the solute comprising a biocompatible polymer, the concentration of polymer in the first liquid being at least 10% w/v, ‘w’ being the weight of the polymer and ‘v’ being the volume of the solvent, providing a plurality of liquid droplet generators operable to generate liquid droplets, providing a jet of a second liquid, causing the plurality of liquid droplet generators to form liquid droplets of the first liquid, passing the liquid droplets through a gas to contact the jet of the second liquid so as to cause the solvent to exit the droplets, thus forming solid microparticles, the solubility of the solvent in the second liquid being at least 5 g of solvent per 100 ml of second liquid, the solvent being substantially miscible with the second liquid.

The invention claimed is: 
     
       1. An apparatus for producing solid polymeric microparticles, the apparatus comprising:
 a plurality of liquid droplet generators for forming liquid droplets of a first liquid, wherein the plurality of liquid droplet generators comprise at least one piezoelectric component operable to generate droplets at a frequency of at least 1 kHz per droplet generator; and 
 a nozzle for forming a jet of a second liquid, 
 
       wherein the plurality of liquid droplet generators and the nozzle are arranged relative to each other such that, in use, liquid droplets from the plurality of liquid droplet generators pass through a gas into said jet of second liquid in a liquid droplet contact zone of said jet of second liquid, and wherein the jet of second liquid is not in contact with any wall or channel for at least the length of said liquid droplet contact zone. 
     
     
       2. The apparatus according to  claim 1 , wherein the plurality of liquid droplet generators are in the form of an inkjet printhead. 
     
     
       3. The apparatus according to  claim 1 , wherein the plurality of liquid droplet generators each comprise a droplet generator outlets and wherein the droplet generator outlets are in a line or an array. 
     
     
       4. The apparatus according to  claim 3 , wherein the line or array of droplet generator outlets is substantially parallel to the jet direction of said nozzle. 
     
     
       5. The apparatus according to  claim 1 , wherein the number of liquid droplet generator outlets is in the range 5 to 2500. 
     
     
       6. The apparatus according to  claim 1 , wherein the plurality of liquid droplet generators are operable to generate liquid droplets having an individual droplet volume in the range 1 to 100 pL. 
     
     
       7. The apparatus according to  claim 1 , further comprising a microparticle-receiving means for receiving solid microparticles dispersed in a jet of liquid. 
     
     
       8. The apparatus according to  claim 1 , further comprising means for generating flow of liquid through said nozzle. 
     
     
       9. The apparatus according to  claim 8 , wherein said means for generating flow comprises a regulated pressure system for producing a pulseless flow of liquid. 
     
     
       10. The apparatus according to  claim 1 , further comprising a camera for monitoring liquid droplets generated by said plurality of liquid droplet generators. 
     
     
       11. The apparatus according to  claim 10 , further comprising a light source for illuminating liquid droplets generated by said plurality of liquid droplet generators. 
     
     
       12. The apparatus according to  claim 11 , wherein said light source comprises an LED strobe electrically coordinated with the plurality of liquid droplet generators such that, in use, the camera is able to capture an image of liquid droplets ejected from the plurality of liquid droplet generators at a pre-determined time period after ejection of said liquid droplets. 
     
     
       13. The apparatus according to  claim 12 , wherein the LED strobe has an adjustable strobe delay, adjustable strobe intensity and/or adjustable pulse width settings, thereby allowing said pre-determined time period after ejection of said droplets to be adjusted. 
     
     
       14. The apparatus according to  claim 1 , further comprising at least one temperature regulator for controlling the temperature of liquid entering said plurality of liquid droplet generators and/or the temperature of liquid entering said nozzle. 
     
     
       15. The apparatus according to  claim 14 , wherein the at least one temperature regulator comprises a first chiller for controlling the temperature of the first liquid entering the plurality of liquid droplet generators in the range of 5° C. to 30° C. 
     
     
       16. The apparatus according to  claim 14 , wherein the at least one temperature regulator comprises a second chiller for controlling the temperature of the second liquid entering the nozzle in the range of 0° C. to 20° C. 
     
     
       17. The apparatus according to  claim 1 , wherein the plurality of liquid droplet generators are positioned relative to the nozzle such that the distance of travel of a liquid droplet from the outlet of a liquid droplet generator to the jet is in the range 2 to 10 mm.